If you are a Small Business customer, find additional troubleshooting and learning resources at the Support for Small Business site.

A side by side install of Office 2013 Click 2 Run (C2R) with Office 2003 is not recommended or supported. Installing Office 2013 C2R on a computer with Office 2003 proceeds without error. When you run Outlook 2003 it will show the following error:

OUTLOOK.EXE - Ordinal Not Found The ordinal 8626 could not be located in the dynamic link library C:\Program Files\Microsoft Office 15\Root\Office15\outlph.dll

You can run a Repair of 2003 (with Office 2013 still installed), however the repair of Outlook 2003 might cause errors when opening Office 2013 files. Additionally, add-ins and other applications that integrate with Microsoft Office programs may not work as expected.